Downlink signal synchronization method and system

Abstract

The present disclosure relates to a downstream signal synchronization method and system, and relates to the field of passive optical networks. The method is applicable to a wavelength division multiplexing passive optical network. Specifically, when an optical network unit (ONU) is in an operating state, it can detect whether a situation where the synchronization of the downstream signal is lost has occurred. The downstream signal includes a management path signal and a data path signal. When a situation occurs where the synchronization of the management path signal is lost and the data path signal is normally synchronized, the ONU switches from the operating state to a management path synchronization loss sub-state, monitors a first recovery time for the ONU to recover the synchronization of the management path signal in the management path synchronization loss sub-state. If the first recovery time does not exceed a first predetermined time threshold and the data path signal is still normally synchronized, the ONU returns from the management path synchronization loss sub-state to the operating state. In this way, it is possible to avoid the problem that the ONU goes out of management due to the absence of a state transition method in the situation corresponding to the original state machine.

Description

Technical Field

[0001] Cross-reference to Related Applications This application claims the priority of a Chinese patent application with application number 202210498932.8 filed on May 9, 2022, and incorporates the entire disclosure of the Chinese patent application herein by reference for all purposes.

[0002] Embodiments of the present disclosure relate to the field of passive optical network technologies, and more specifically, to a downstream signal synchronization method and system.

Background Art

[0003] The high-speed passive optical network (PON) technology widely deployed and applied in existing networks mainly uses time-division multiplexed EPON (Ethernet Passive Optical Network) or GPON (Gigabit-Capable PON) systems. The upstream and downstream links operate at a single wavelength and are transmitted by a mechanism that assigns each transmission time. The wavelength division multiplexing passive optical network (WDM-PON) uses wavelength division multiplexing (WDM) technology. The PON port of the optical line terminal (OLT) on the central office side and the optical network unit (ONU) on the user side each exclusively occupy a pair of wavelength paths point-to-point. The number of accessible users is several times that of the conventional time-division PON. It mainly provides network connections for government and enterprise users, wireless bearers, etc. Especially in the 5G fronthaul field, using WDM-PON can save backbone optical fiber resources and reduce the cost and difficulty of network implementation, maintenance, and operation.

[0004] In a conventional PON, the process of activating ONU registration, due to the characteristics of time-division multiplexing, involves states such as distance measurement and time slot allocation, which are not required in a wavelength-division multiplexing-based WDM-PON. Currently, in existing WDM-PON systems, the basic frame of the ONU registration activation process directly uses the conventional PON. When the ONU startup state machine is in an operating state, the state machine defines a state transition method only for situations where the synchronization of the data path is lost.

[0005] Note that the information disclosed in the above background art section is only for enhancing the understanding of the background of the present disclosure and may include information that does not constitute the prior art known to those skilled in the art.

Summary of the Invention

[0006] According to one aspect of the present disclosure, there is provided a downstream signal synchronization method applicable to a wavelength-division multiplexed passive optical network. The method includes: When an optical network unit (ONU) is in an operating state, detecting whether a situation where the synchronization of the downstream signal is lost has occurred, where the downstream signal includes a management path signal and a data path signal; When a situation occurs where the synchronization of the management path signal is lost and the data path signal is normally synchronized, the ONU switches from the operating state to a management path synchronization loss sub-state; Monitoring, in the management path synchronization loss sub-state, a first recovery time for the ONU to recover the synchronization of the management path signal; When the first recovery time does not exceed a first predetermined time threshold and the data path signal is still normally synchronized, the ONU returns from the management path synchronization loss sub-state to the operating state, whereby the ONU continues to operate in the operating state.

[0007] In some embodiments, after monitoring, in the management path synchronization loss sub-state, a first recovery time for the ONU to recover the synchronization of the management path signal, the method includes: When a situation occurs where the synchronization of the data path signal is lost within the first predetermined time threshold, the ONU further includes switching from the management path synchronization loss sub-state to a temporary data path synchronization loss LODS state.

[0008] In some embodiments, the method includes, after the ONU monitors a first recovery time for recovering the synchronization of the management path signal in the management path synchronization loss sub-state, when the first recovery time exceeds the first predetermined time threshold, the ONU further includes switching from the management path synchronization loss sub-state to a temporary data path synchronization loss LODS state.

[0009] In some embodiments, the method includes monitoring a second recovery time of the management path signal and the data path signal of the ONU in the temporary LODS state, when the second recovery time does not exceed a second predetermined time threshold, returning the ONU to the operating state and continuing the operation, and when the second recovery time exceeds the second predetermined time threshold, the ONU further includes entering an initial state of the downstream signal synchronization.

[0010] In some embodiments, in the management path synchronization loss sub-state, the data path signal of the ONU synchronizes and operates normally.

[0011] According to one aspect of the present disclosure, a downstream signal synchronization system applied to a wavelength division multiplexing passive optical network is provided, and the system is used to detect whether a situation occurs where the synchronization of the downstream signal is lost when an optical network unit ONU is in an operating state, and the downstream signal includes a management path signal and a data path signal, and a detection module, and a first switching module used to switch the ONU from the operating state to a management path synchronization loss sub-state when a situation occurs where the synchronization of the management path signal is lost and the data path signal is synchronizing normally. A first monitoring module used to monitor a first recovery time for the ONU to recover synchronization of the management path signal in the management path synchronization loss sub-state; A first return module used when the first recovery time does not exceed a first predetermined time threshold and the data path signal is still normally synchronized, so that the ONU returns from the management path synchronization loss sub-state to the operating state, and thereby the ONU continues to operate in the operating state. The system includes:

[0012] In some embodiments, the system Further includes a second switching module used to switch the ONU from the management path synchronization loss sub-state to a temporary data path synchronization loss LODS state when a situation where the synchronization of the data path signal is lost occurs within the first predetermined time threshold.

[0013] In some embodiments, the system Further includes a second switching module used to switch the ONU from the management path synchronization loss sub-state to a temporary data path synchronization loss LODS state when the first recovery time exceeds the first predetermined time threshold.

[0014] In some embodiments, the system In the temporary LODS state, monitor a second recovery time for the ONU to recover the management path signal and the data path signal. When the second recovery time does not exceed a second predetermined time threshold, the ONU returns to the operating state and continues to operate. When the second recovery time exceeds the second predetermined time threshold, the system further includes a second monitoring module used for the ONU to enter the initial state of the downstream signal synchronization.

[0015] In some embodiments, in the management path synchronization loss sub-state, the data path signal of the ONU is synchronized and operates normally.

[0016] According to one aspect of the present disclosure, there is provided a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the downlink signal synchronization method according to any one of the above items is realized.

[0017] It should be noted that the above general description and the following detailed description are merely exemplary and explanatory, and do not limit the present disclosure.

Brief Description of the Drawings

[0018] The drawings here are incorporated into the specification and form a part of the specification, showing embodiments that conform to the present disclosure, and are used to interpret the principles of the present disclosure together with the specification. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

Figure 1

Figure 2

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Figure 4

Embodiments for Carrying Out the Invention

[0019] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments can be embodied in many forms and should not be construed as limited to the examples set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The features, structures, or characteristics described may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of the present disclosure. However, as will be understood by those skilled in the art, one or more of the specific details may be omitted in implementing the technical solution of the present disclosure, or other methods, components, devices, steps, etc. may be used. In other cases, well-known technical solutions are not shown or described in detail to avoid obscuring aspects of the present disclosure.

[0020] Note that the drawings are only schematic diagrams of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures denote the same or similar parts, and redundant descriptions are omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in the form of software, or in the form of one or more hardware modules or integrated circuits, or in the form of different networks and / or processor devices and / or microcontroller devices.

[0021] In a wavelength division multiplexed passive optical network (WDM-PON), a user data path and a management client path are separately transmitted through a transmission convergence layer (TC) in the transmission convergence layer. Here, user data is not processed by the TC layer, and management data is processed by the TC layer in a specific manner. The transmission method is divided into two modes: transcoded transmission and transparent transmission. Therefore, in the ONU registration activation process of the wavelength division multiplexed passive optical network (WDM-PON), embodiments of the present disclosure mainly include an initial state (Initial state), a serial number state (Serial Number state), an operation state (Operation state), and an intermittent loss of data path synchronization state (Intermittent LODS state).

[0022] In the initial state (O1), when the ONU is powered on for the first time or restarted, the ONU enters the initial state (O1). While in the initial state (O1), the ONU can perform an operation of turning on the receiver and turning off the transmitter. The initial state (O1) may further include an asynchronous sub-state (Off-Sync, O1.1) and a profile learning sub-state (ProfileLearning, O1.2). The asynchronous sub-state (O1.1) may be an entry of the initial state (O1), or the ONU may enter the asynchronous sub-state (O1.1) when trying to synchronize on the PON wavelength path. The profile learning sub-state (O1.2) may be used to determine whether the wavelength path is available by the ONU acquiring profile information through the downstream PLOAM message. When it is determined that the downstream synchronization of the wavelength path is successful, the ONU can enter the profile learning sub-state (O1.2).

[0023] The serial number state (O2-3) may be the transmitter at the ONU startup. The serial number state (O2-3) may be used to provide authentication information by the ONU periodically transmitting specific PLOAM (physical Layer Operations, Administration and Maintenance) messages until the OLT CT confirms the assignment of the ONU-ID. When the time for the ONU to be in the serial number state (O2-3) times out, the ONU can return from the serial number state (O2-3) to the initial state (O1).

[0024] The operating state (O5) may be used for the ONU to transmit and receive signals via the PON path. In some embodiments of the present disclosure, the operating state (O5) may further include a management path synchronization loss (Lossof downstream synchronization inthe management TC data path, MLODS) sub-state (which may be referred to as O5.1, O5.3). Specifically, when a situation occurs where the synchronization of the data path signal of the ONU in the operating state (O5) is normal but the synchronization of the management path signal is lost, the ONU can enter the management path synchronization loss sub-state (O5.3). After entering the management path synchronization loss sub-state (O5.3), the ONU can start a timer TO1 (which may be referred to as TOM), and the timer TO1 records the time when the ONU is in the management path synchronization loss sub-state (O5.3). If the ONU recovers the synchronization of the management path signal before TO1 times out, the ONU returns to the operating state (O5). If TO1 times out, the ONU stops data transmission and enters the intermittent data path synchronization loss state (IntermittentLODS state, O6).

[0025] The temporary data path synchronization loss state (O6) may enter this temporary data path synchronization loss state (O6) after the operating state (O5), that is, when the ONU in the operating state (O5) loses the synchronization of the data path signal or the time in the management path synchronization loss state (O5.3) times out. This temporary data path synchronization loss state may also be abbreviated as the temporary LODS state.

[0026] Specifically, after the ONU accesses and is powered on, it enters the initial state (O1), starts ONU activation, that is, the ONU synchronizes its receiver, searches for the wavelength of the downstream path, synchronizes with the data and management paths, collects profile information, and executes operations to confirm the basic parameters. After the ONU determines the wavelength of the downstream path, the ONU synchronizes its transmitter and declares its existence by a specific message for authentication. After the OLTCT succeeds in authenticating the ONU, it is confirmed by a specific message, and thereby the ONU enters the operating state (O5). When a situation occurs where the ONU in the operating state (O5) loses the downstream synchronization of the data path, the ONU enters the temporary LODS state (O6). In the temporary LODS state (O6), it can be detected whether the time required to restore the synchronization of the data path signal and the management path signal is smaller than a preset threshold. If the required time is smaller than the preset threshold, that is, if the ONU succeeds in restoring the synchronization of the data path signal and the management path signal within the preset threshold, the ONU can return to the operating state (O5). If the required time is larger than the preset threshold, that is, if the ONU fails to restore the synchronization of the data path signal and the management path signal within the preset threshold, the ONU can return to the asynchronous sub-state (O1.1) in the initial state (O1) and restart. When the ONU in the operating state (O5) loses the synchronization of the management path but the data path is still being normally transmitted and received, there is no corresponding state transition method in the related art, so the ONU may be disconnected from the management.

[0027] FIG. 1 shows the ONU registration activation process of a wavelength division multiplexed passive optical network in the related art. As shown in FIG. 1, 01. For an ONU in the asynchronous sub-state (O1.1), when the downstream signal recovers synchronization (DSYNC), that is, both the data path signal and the management path signal recover synchronization, it enters the profile learning sub-state (O1.2). 02. For an ONU in the profile learning sub-state (O1.2), if the data path synchronization loss (LODS) or the downstream wavelength path (DWLCH) does not match, it enters the asynchronous sub-state (O1.1). 03. For an ONU in the initial state (O1), if the downstream wavelength path (DWLCH) can operate normally, it enters the serial number state (O2-3). 04. For an ONU in the serial number state (O2-3), when it executes the assignment of the ONU-ID, it enters the operating state (O5). 05. For an ONU in the operating state (O5), when a data path synchronization loss (Loss of downstream synchronization, LODS) occurs, it enters the temporary LODS state (O6). 06. For an ONU in the temporary LODS state (O6), when the downstream signal recovers synchronization (DSYNC), that is, both the data path signal and the management path signal recover synchronization, it enters the temporary LODS state (O6). 07. For an ONU in the serial number state (O2-3), if any of the situations of data path synchronization loss, timeout of the residence time in the serial number state (O2-3), and cancellation of the ONU-ID request occur, it enters the asynchronous sub-state (O1.1). 08. For an ONU in the operating state (O5), when the ONU-ID request is cancelled, it enters the asynchronous sub-state (O1.1). 09. For an ONU in the temporary LODS state (O6), when the residence time in the temporary LODS state (O6) times out, it enters the asynchronous sub-state (O1.1).

[0028] FIG. 2 is a step flowchart of a downstream signal synchronization method according to an embodiment of the present disclosure, which is applied to a wavelength division multiplexed passive optical network. As shown in FIG. 2, the method may include steps S101 to S104.

[0029] In step S101, when the optical network unit ONU is in an operating state, it detects whether a situation where the synchronization of the downstream signal is lost has occurred. The downstream signal includes a management path (management TC data path) signal and a data path signal.

[0030] In some embodiments of the present disclosure, the optical network unit ONU enters an operating state in the ONU registration activation process. When in the operating state, it is necessary to synchronize the downstream signal. During the synchronization process, the synchronization of the management path signal may be lost, the synchronization of the data path signal may be lost, or the synchronization of both the management path signal and the data path signal may be lost. Therefore, by detecting whether the synchronization of the downstream signal is lost, the problem of signal synchronization loss can be timely solved, and the problem of the ONU being out of management due to signal synchronization loss can be avoided.

[0031] In step S102, when a situation occurs where the synchronization of the management path signal is lost and the data path signal is synchronizing normally, the ONU switches from the operating state to a management path synchronization loss sub-state.

[0032] In some embodiments of the present disclosure, since the ONU is currently in an operating state, when a situation occurs where the synchronization of the management path signal is lost and the data path signal is synchronizing normally, the ONU can enter a management path synchronization loss sub-state from the operating state. This management path synchronization loss sub-state may also be abbreviated as the MLODS sub-state. In the MLODS sub-state, the synchronization of the data path of the ONU is normal, that is, user data can be normally transmitted and received without being affected by the MLODS sub-state.

[0033] In step S103, in the management path synchronization loss sub-state, the ONU monitors a first recovery time for recovering the synchronization of the management path signal.

[0034] In some embodiments of the present disclosure, when the ONU is in the MLODS sub-state, the time for recovering the synchronization of the management path signal is recorded to obtain a first recovery time, and it can be monitored in real time whether the first recovery time exceeds a first predetermined time threshold. The first recovery time may be for recording the time when the ONU is in the MLODS sub-state, and the first predetermined time threshold may be for limiting the time that the ONU stays in the MLODS sub-state and attempts to recover the synchronization of the management path according to the actual situation. Thereby, the problem that the time staying in the management path synchronization loss state is too long and the ONU gets out of management in the MLODS sub-state can be avoided. Note that in the MLODS sub-state, the ONU only fails to synchronize the management path signal, and the synchronization of the data path signal is normal. Therefore, in the MLODS sub-state, the data path can still operate normally, that is, the transmission and reception of user data can still operate normally.

[0035] In some embodiments, the ONU turns on a first timer (such as TOM in the foregoing embodiments), where the duration of the first timer is set to the first predetermined time threshold. The ONU determines whether the first timer times out when the synchronization of the management path signal is recovered, thereby determining whether the first recovery time for the ONU to recover the synchronization of the management path signal in the management path synchronization loss sub-state exceeds the first predetermined time threshold.

[0036] In step S104, when the first recovery time does not exceed the first predetermined time threshold and the data path signal is still synchronizing normally, the ONU returns from the management path synchronization loss sub-state to the operating state, whereby the ONU continues to operate in the operating state.

[0037] In some embodiments of the present disclosure, when the first recovery time does not exceed the first predetermined time threshold, that is, when the management path signal recovers synchronization within the first predetermined time threshold and the data path signal remains normally synchronized, the ONU can be returned from the MLODS sub-state to the operating state. Thereby, the ONU can continue to operate normally in the operating state and perform normal transmission and reception operations on the downstream signal.

[0038] As described above, the downstream signal synchronization method provided by the embodiments of the present disclosure is applied to a wavelength division multiplexing passive optical network. When the optical network unit ONU is in the operating state, it can detect whether a situation where the synchronization of the downstream signal is lost has occurred. The downstream signal includes a management path signal and a data path signal. When a situation occurs where the synchronization of the management path signal is lost and the data path signal remains normally synchronized, the ONU switches from the operating state to the management path synchronization loss sub-state. In the management path synchronization loss sub-state, the ONU monitors the first recovery time for the ONU to recover the synchronization of the management path signal. When the first recovery time does not exceed the first predetermined time threshold and the data path signal still remains normally synchronized, the ONU returns from the management path synchronization loss sub-state to the operating state. Thereby, the ONU can continue to operate normally in the operating state. In this way, by introducing a sub-state where only the synchronization of the management path is lost in the operating state, it compensates for the fact that the conventional ONU registration activation state mechanism does not consider the situation where the synchronization of the management path signal is lost, and avoids the problem that the ONU goes out of management due to the lack of a state transition method in the situation corresponding to the original state machine.

[0039] In some embodiments, the method further includes that after monitoring the first recovery time for the ONU to recover the synchronization of the management path signal in the management path synchronization loss (MLODS) sub-state, when a situation occurs where the synchronization of the data path signal is lost within the first predetermined time threshold, the ONU switches from the management path synchronization loss (MLODS) sub-state to the temporary data path synchronization loss (LODS) state.

[0040] In some embodiments of the present disclosure, when the ONU is in the MLODS sub-state, it may be the case that the synchronization of the data path signal is lost, that is, it may be the case that the synchronization of the data path signal is lost within the first predetermined time threshold. Since both the synchronization of the data path signal and the management path signal of the ONU are lost, the ONU can directly switch to the temporary LODS state and attempt to recover the synchronization of the downstream signal.

[0041] In some embodiments, the method further includes monitoring, in the management path synchronization loss (MLODS) sub-state, a first recovery time for the ONU to recover the synchronization of the management path signal, and when the first recovery time exceeds the first predetermined time threshold, the ONU switching from the management path synchronization loss (MLODS) sub-state to a temporary data path synchronization loss (LODS) state.

[0042] In some embodiments of the present disclosure, it may be the case that the first recovery time for recovering the synchronization of the management path signal exceeds the first predetermined time threshold, that is, it may be the case that the synchronization of the management path signal cannot be recovered within the first predetermined time threshold. The ONU can be returned from the MLODS sub-state to the temporary LODS state, whereby the ONU can attempt to recover the synchronization of the downstream signal in the temporary LODS state.

[0043] In some embodiments, the downstream signal synchronization method in the embodiments of the present disclosure further includes monitoring a second recovery time of the management path signal and the data path signal of the ONU in the temporary LODS state, when the second recovery time does not exceed a second predetermined time threshold, the ONU returning to the operating state and continuing to operate, and when the second recovery time exceeds the second predetermined time threshold, the ONU entering the initial state of the downstream signal synchronization.

[0044] In some embodiments of the present disclosure, for an ONU in a temporary LODS state, record the time for the ONU to recover the management path signal and the data path signal, obtain a second recovery time, detect the second recovery time, and determine whether the second recovery time exceeds a second predetermined time threshold. Here, the second recovery time may be the time when the ONU is in the temporary LODS state, and the second predetermined time threshold may be the time for restricting the ONU from staying in the LODS state. The specific numerical value may be specifically set according to the actual situation.

[0045] In some embodiments, the ONU turns on a second timer (TOL), where the duration of the second timer is set to the second predetermined time threshold. The ONU determines whether the second timer times out when the management path signal and the data path signal are recovered, so as to determine whether the second recovery time for the ONU to recover the management path signal and the data path signal in the temporary LODS state exceeds the second predetermined time threshold.

[0046] In some embodiments of the present disclosure, when the second recovery time does not exceed the second predetermined time threshold, that is, within the second predetermined time threshold, when the synchronization of the management path signal and the synchronization of the data path signal of the ONU are both normally recovered, the ONU can return from the temporary LODS state to the operating state and continue normal operation. When the second recovery time exceeds the second predetermined time threshold, that is, within the second predetermined time threshold, when the synchronization of the management path signal and the synchronization of the data path signal of the ONU cannot be recovered, the ONU can directly enter the initial state of the downstream signal synchronization.

[0047] Exemplarily, FIG. 3 is a flowchart of ONU synchronization recovery provided by an embodiment of the present disclosure. As shown in FIG. 3, 11. When the ONU in the operating state (O5) experiences a situation where the synchronization of the management path is lost and the data path is operating normally, it enters the MLODS sub-state (O5.3), attempts to recover synchronization within a certain period of time, and at this time, the transmission and reception of user data are still carried out normally without being affected. 12. When the ONU in the MLODS sub-state (O5.3) recovers the synchronization of the management path signal normally and the synchronization of the data path signal is still operating normally, it returns to the operating state (O5). 13. When the ONU in the MLODS sub-state (O5.3) exceeds the second predetermined time threshold for the synchronization recovery of the management path or a situation occurs where the synchronization of the data path is lost within the second predetermined time threshold, it enters the temporary LODS state (O6) to perform the synchronization recovery of the data path. 14. When the ONU in the operating state (O5) loses the synchronization of the data path, since it cannot guarantee the normal transmission and reception of user data at this time, it directly enters the temporary LODS state (O6) to perform the synchronization recovery of the data path. 15. When the ONU in the temporary LODS state (O6) recovers the synchronization of the data path and the management path normally, it returns to the operating state (O5).

[0048]

Table 1

[0049] Exemplarily, Table 1 shows events that can be used for state transitions in the embodiments of the present disclosure. When a situation occurs where the synchronization of the management path signal is lost when the ONU is in the operating state O5, the first predetermined time threshold is turned on, and the state is switched to the MLODS sub-state. The management path synchronization loss state O5.3 and the LODS state O6 are not applicable to the MLODS sub-state. In the management path synchronization loss state O5.3, when management path synchronization recovery (MDSYNC) occurs, the first predetermined time threshold can be turned on, and the state can be switched to the operating state O5. The operating state O5 and the LODS state O6 are not applicable to MDSYNC. In the management path synchronization loss state O5.3, when LODS occurs, that is, when a situation occurs where the synchronization of the data path signal is lost, the second predetermined time threshold can be turned on, and the state can be switched to the LODS state O6. The LODS state O6 is not applicable to LODS. Downlink synchronization recovery (DSYNC) is not applicable to the operating state O5 and the management path synchronization loss state O5.3. In the LODS state O6, when DSYNC occurs, the second predetermined time threshold can be stopped, and the state can be switched to the operating state O5. In the management path synchronization loss state O5.3, when a time-out of the first predetermined time threshold occurs, the second predetermined time threshold can be turned on, and the state can be switched to the LODS state O6. The time-out of the first predetermined time threshold is not applicable to the operating state O5 and the LODS state O6. In the LODS state O6, when a time-out of the second predetermined time threshold occurs, the ONU-ID value can be discarded, and the state can be switched to asynchronous O1.1 (i.e., restart).

[0050] FIG. 4 is a downlink signal synchronization system according to an embodiment of the present disclosure. As shown in FIG. 4, the system 30 may include a detection module 301, a first switching module 302, a first monitoring module 303, and a first return module 304.

[0051] The detection module 301 is used to detect whether a situation occurs where the synchronization of the downlink signal is lost when the optical network unit ONU is in the operating state. The downlink signal includes a management path signal and a data path signal.

[0052] When the synchronization of the management path signal is lost and the data path signal is in normal synchronization, the first switching module 302 is used for the ONU to switch from the operating state to the management path synchronization loss sub-state.

[0053] The first monitoring module 303 is used to monitor the first recovery time for the ONU to recover the synchronization of the management path signal in the management path synchronization loss sub-state.

[0054] When the first recovery time does not exceed the first predetermined time threshold and the data path signal is still in normal synchronization, the first return module 304 is used for the ONU to return from the management path synchronization loss sub-state to the operating state, so that the ONU continues to operate in the operating state.

[0055] As described above, the downstream signal synchronization system provided by the embodiments of the present invention is applied to a wavelength division multiplexing passive optical network. When the optical network unit ONU is in the operating state, it can detect whether the synchronization of the downstream signal is lost. The downstream signal includes a management path signal and a data path signal. When the synchronization of the management path signal is lost and the data path signal is in normal synchronization, the ONU switches from the operating state to the management path synchronization loss sub-state. In the management path synchronization loss sub-state, the first recovery time for the ONU to recover the synchronization of the management path signal is monitored. When the first recovery time does not exceed the first predetermined time threshold and the data path signal is still in normal synchronization, the ONU returns from the management path synchronization loss sub-state to the operating state, so that the ONU continues to operate normally in the operating state. In this way, by introducing a sub-state where only the synchronization of the management path is lost in the operating state, it makes up for the fact that the conventional ONU registration activation state mechanism does not consider the situation where the synchronization of the management path signal is lost, and avoids the problem that the ONU is out of management due to the lack of a state transition method in the situation corresponding to the original state machine.

[0056] In some embodiments, when a situation occurs where the synchronization of the data path signal is lost within the first predetermined time threshold, the system 30 further includes a second switching module used for the ONU to switch from the management path synchronization loss sub-state to a temporary data path synchronization loss (LODS) state.

[0057] In some embodiments, when the first recovery time exceeds the first predetermined time threshold, the system 30 further includes a second switching module used for the ONU to switch from the management path synchronization loss sub-state to a temporary data path synchronization loss (LODS) state.

[0058] In some embodiments, in the temporary LODS state, the system 30 monitors the second recovery time of the management path signal and the data path signal of the ONU. When the second recovery time does not exceed the second predetermined time threshold, the ONU returns to the operating state and continues to operate. When the second recovery time exceeds the second predetermined time threshold, the system 30 further includes a second monitoring module used for the ONU to enter the initial state of the downstream signal synchronization.

[0059] In some embodiments, in the management path synchronization loss sub-state, the data path signal of the ONU synchronizes and operates normally. Since the specific details of each module in the above downstream signal synchronization system are described in detail in the corresponding downstream signal synchronization method, the description is omitted here.

[0060] It should be noted that in the above detailed description, some modules or units of the device for executing actions are mentioned, but it should be noted that such a division is not essential. In fact, according to the embodiments of the present disclosure, the features and functions of the above two or more modules or units may be embodied in one module or unit. Conversely, the features and functions of the above one module or unit may be further divided and embodied in a plurality of modules or units.

[0061] Also, although each step of the method in the present disclosure has been described in a specific order in the drawings, this does not require or imply that these steps must be executed in this specific order or that all the steps shown must be executed. Additionally or alternatively, some steps may be omitted, multiple steps may be integrated and executed as one step, and / or one step may be decomposed and executed as multiple steps, etc.

[0062] In an exemplary embodiment of the present disclosure, an electronic device capable of implementing the above method is further provided.

[0063] As can be understood by those skilled in the art, each aspect of the present disclosure may be implemented as a system, method, or program product. Therefore, each aspect of the present disclosure may specifically be implemented in the form of a complete hardware embodiment, a complete software embodiment (including firmware, microcode, etc.), or an embodiment combining hardware and software aspects, where it may be collectively referred to as a "circuit", "module", or "system".

[0064] From the description of the above embodiments, those skilled in the art can easily understand that the exemplary embodiments described herein may be implemented by software or by a combination of software and the necessary hardware. Therefore, the technical solution according to the embodiments of the present disclosure may be embodied in the form of a software product, and the software product may be stored in a non-volatile storage medium (which may be a CD-ROM, a USB disk, a portable hard disk, etc.) or on a network, and includes several instructions for causing a computing device (which may be a personal computer, a server, a terminal device, or a network device, etc.) to execute the method according to the embodiments of the present disclosure.

[0065] In an exemplary embodiment of the present disclosure, there is further provided a computer-readable storage medium storing a program product capable of implementing the above method of this specification. In some possible embodiments, each aspect of the present disclosure may be implemented in the form of a program product including program code. When the program product is executed on a terminal device, the program code is used to cause the terminal device to execute the steps according to various exemplary embodiments of the present disclosure described in the "Exemplary Method" section of this specification.

[0066] The program product for implementing the above method according to an embodiment of the present disclosure may employ a portable compact disc read-only memory (CD-ROM), include program code, and be executable on an end device such as a personal computer. However, the program product of the present disclosure is not limited thereto. In this specification, a readable storage medium may be any tangible medium that includes or stores a program used by or in combination with an instruction execution system, apparatus, or device.

[0067] The program product may employ any combination of one or more readable media. The readable media may be a readable signal medium or a readable storage medium. The readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (non-exhaustive list) of the readable storage medium include an electrical connection having one or more conductors, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0068] A computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier, and carry therein a program code readable by a computer. Such propagated data signals may take various forms, including, but not limited to, electromagnetic signals, optical signals, or any suitable combination of the foregoing. The readable signal medium may be any readable medium other than a readable storage medium, and the readable medium can transmit, propagate, or transmit a program for use by or in combination with an instruction execution system, apparatus, or device.

[0069] The program code contained in the readable medium can be transmitted over any appropriate medium, including, but not limited to, wireless, wired, optical cable, RF, or any suitable combination of the foregoing.

[0070] Program code for performing the operations of this disclosure can be created in any combination of one or more programming languages, including object-oriented programming languages such as Java, C++, and further including conventional procedural programming languages such as the "C" language or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, may be executed as a stand-alone software package, may be executed partially on the user computing device and partially on a remote computing device, or may be executed entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device via any type of network including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computing device (e.g., connected via the Internet using an Internet service provider).

[0071] It should be noted that the above drawings are merely schematic descriptions of the processes included in the method according to the exemplary embodiments of the present disclosure and are not for limitation. For ease of understanding, the processes shown in the above drawings do not indicate or limit the chronological order of these processes. Also, it is easily understood that these processes may be executed synchronously or asynchronously by, for example, a plurality of modules.

[0072] Those skilled in the art can easily conceive of other embodiments of the present disclosure after considering the specification and practicing the inventions disclosed herein. This application is intended to cover any modifications, uses, or adaptive changes of the present disclosure, and these modifications, uses, or adaptive changes include well-known common general knowledge or ordinary technical means in the art not invented in the present disclosure in accordance with the general principles of the present disclosure. The specification and examples are merely illustrative, and the true scope and spirit of the present disclosure are indicated by the claims.

Claims

1. A downstream signal synchronization method applied to a wavelength division multiplexed passive optical network, comprising: when an optical network unit (ONU) is in an operating state, detecting whether a situation where the synchronization of the downstream signal is lost has occurred, wherein the downstream signal includes a management path signal and a data path signal; when a situation occurs where the synchronization of the management path signal is lost and the data path signal is normally synchronized, the ONU switches from the operating state to a management path synchronization loss sub-state; monitoring, in the management path synchronization loss sub-state, a first recovery time for the ONU to recover the synchronization of the management path signal; when the first recovery time does not exceed a first predetermined time threshold and the data path signal is still normally synchronized, the ONU returns from the management path synchronization loss sub-state to the operating state, whereby the ONU continues to operate in the operating state.

2. The method further comprises: after monitoring, in the management path synchronization loss sub-state, a first recovery time for the ONU to recover the synchronization of the management path signal, when a situation occurs where the synchronization of the data path signal is lost within the first predetermined time threshold, the ONU further switches from the management path synchronization loss sub-state to a temporary data path synchronization loss (LODS) state.

3. The method further comprises: after monitoring, in the management path synchronization loss sub-state, a first recovery time for the ONU to recover the synchronization of the management path signal, when the first recovery time exceeds the first predetermined time threshold, the ONU further switches from the management path synchronization loss sub-state to a temporary data path synchronization loss (LODS) state.

4. The method further comprises: monitoring, in the temporary LODS state, a second recovery time for the management path signal and the data path signal of the ONU; when the second recovery time does not exceed a second predetermined time threshold, the ONU returns to the operating state and continues to operate.

5. The method further comprises: when the second recovery time exceeds the second predetermined time threshold, the ONU enters an initial state of the downstream signal synchronization.

6. The downstream signal synchronization method according to claim 1, wherein in the management path synchronization loss sub-state, the data path signal of the ONU synchronously operates normally.

7. Monitoring, in the management path synchronization loss sub-state, a first recovery time for the ONU to recover the synchronization of the management path signal includes: The ONU turns on a first timer, and a duration of the first timer is set to the first predetermined time threshold; The ONU determines whether the first timer times out when the synchronization of the management path signal is recovered, so as to determine whether a first recovery time for the ONU to recover the synchronization of the management path signal in the management path synchronization loss sub-state exceeds the first predetermined time threshold. The downstream signal synchronization method according to claim 1 includes the above.

8. Monitoring, in the temporary LODS state, a second recovery time for the ONU to recover the management path signal and the data path signal includes: The ONU turns on a second timer, and a duration of the second timer is set to the second predetermined time threshold; The ONU determines whether the second timer times out when the management path signal and the data path signal are recovered, so as to determine whether a second recovery time for the ONU to recover the management path signal and the data path signal in the temporary LODS state exceeds the second predetermined time threshold. The downstream signal synchronization method according to claim 4 or 5 includes the above.

9. A downstream signal synchronization system applied to a wavelength division multiplexing passive optical network, comprising: A detection module used to detect whether a situation where the synchronization of a downstream signal is lost occurs when an optical network unit ONU is in an operating state, where the downstream signal includes a management path signal and a data path signal; A first switching module used to switch the ONU from the operating state to a management path synchronization loss sub-state when a situation where the synchronization of the management path signal is lost and the data path signal is synchronously operating normally occurs; A first monitoring module used to monitor a first recovery time for the ONU to recover the synchronization of the management path signal in the management path synchronization loss sub-state; When the first recovery time does not exceed a first predetermined time threshold and the data path signal remains in normal synchronization, the ONU returns from the management path synchronization loss sub-state to the operating state, and thus the ONU is used to continue operating in the operating state, including a first return module. A downstream signal synchronization system.

10. The system is When a situation occurs in which the synchronization of the data path signal is lost within the first predetermined time threshold, the ONU is used to switch from the management path synchronization loss sub-state to a temporary data path synchronization loss LODS state. The downstream signal synchronization system according to claim 9, further comprising a second switching module.

11. The system is When the first recovery time exceeds the first predetermined time threshold, the ONU is used to switch from the management path synchronization loss sub-state to a temporary data path synchronization loss LODS state. The downstream signal synchronization system according to claim 9, further comprising a second switching module.

12. The system is In the temporary LODS state, the ONU monitors a second recovery time for recovering the management path signal and the data path signal. When the second recovery time does not exceed a second predetermined time threshold, the ONU returns to the operating state and continues to operate. When the second recovery time exceeds the second predetermined time threshold, the downstream signal synchronization system according to claim 10 or 11, further comprising a second monitoring module used for the ONU to enter the initial state of the downstream signal synchronization.

13. In the management path synchronization loss sub-state, the data path signal of the ONU synchronizes and operates normally. The downstream signal synchronization system according to claim 9.

14. A downstream signal synchronization device, comprising: A processor; A memory connected to the processor and used for storing instructions. When the instructions are executed by the processor, the processor is caused to execute the method according to any one of claims 1 to 8. A downstream signal synchronization device comprising a memory.

15. A computer-readable storage medium storing a computer program, When the computer program is executed by a processor, a computer-readable storage medium in which the downstream signal synchronization method according to any one of claims 1 to 8 is realized.

16. A computer program comprising instructions which, when executed by a processor, cause the processor to perform the method according to any one of claims 1 to 8. A computer program, wherein when the instructions are executed by a processor, the processor is caused to execute the method according to any one of claims 1 to 8.

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